Manufacture of electric filaments.



UNITED STATES PATENT OFFICE...

CARL AUER voii WELSBACH, OF VIENNA, AUSTRIA-HUNGARY.

MANUFACTURE 013 ELECTRIC FILAMENTQ.

Specification of Letters Patent.

No Drawing. Application filed August 24, 1899. Serial No. 728,358.

tria-Hungary, residing at Vienna, Austria-3 Hungary, have invented or discovered a certain new and useful Improvement in the Manufacture of Electric Filaments, of Which the following is a specification.

My invention relates to the production of filaments containing osmium alloyed with another metal or metals and from which the disturbing occluded gases as for example, hydrogen, carbonic acid, carbon dioxid and hydro-carbon gases 'are eliminated in the course of the manufacture of the filaments, except, perhaps, some such slight residue of gases as can notbe driven off at dazzling incandescence. t

In a companion application filed of even date herewith, No. 728,356 I have described theproduction of filaments of osmium alloy by coating a somewhat porous osmium filament with a light layer of a magma consisting of an emulsion in water of the oxid of the metal to be alloyed or said oxid associated with carbon, the resultant product being either, an osmium alloy filament containing a small percentage of the alloying metal or in addition thereto a small percentage of carbon. In said application, I have noted the fact that the filaments therein described, although containing but a small proportion of alloying metal, are somewhat more elastic than the pure osmium filament itself. It may be said generally of osmium alloy filaments that by increasing the percentage of the alloy metal up to a certain point, their elasticity may be correspondingly increased and I have ascertainedalso that many of these alloys possess the requisite resistance to temperatures when heated to white incandescence by the electric current.

In certain applications for Letters Patent filed by me August 9, 1898, as, for instance, Serial Number 688,201, I have described the production from a paste, of filaments consisting of osmium and a metallic oxid. In the present instance, for the production of osmium alloys, I may start with a paste of the character referred to, in which paste I have incorporated a quantity of carbon sufficient to ultimately reduce the oxid present and proceed to obtain a preliminary filament containing osmium, a metallic oxid and the necessary carbon for the ultimate reduction of the oxid. This preliminary filament I ;first bring to incandescence in a closed exhausted receiver or in reducing gases'( as, for instance, hydro-carbon gases) and subsequently, preferably in cacao, heat the filament by the electric current to the reduction temperature of the oxid.

With this general statement, I will now proceed to give a particular'example of the production of a filament consisting of an alloy of zirconium and osmium, in which the two metals are present in about equal parts.

The preliminary filament, produced from the paste and consisting of zirconium oxid,

- osmium, and carbon is almost black. I first bring the filament -to incandescence in a closed exhausted receiver by thepassage of an electric current, raising the temperature by increasing the current (preferably in.

cacao) until dazzling incandescence is reached, which corresponds to the reduction temperature of the oxid. An energetic development of gas thereupon begins. The filament contracts considerably and its condevelopment of gas ceases, the end of the reduction process is reached. The resultant filament, consisting of an alloy of zirconium and osmium, is almost silver White and is highly elastic in the cold. It is flexible at white incandescence and in a higher degree than a pure osmium filament. It can be heated in vacuo or in highly'reduciug gases up to high temperatures without disintegrating or losing its shape. It is remarkable also for its high resistance to chemical agencies; boiling water and diluted acids do not attack it. 'This shows that the zirconium has fully alloyed itself with the osmium. If highly heated in the air the filament, in consequence of the combustion of the zirconium, flames up brightly for a moment. If we burn out the osmium by inserting the filament in the oxidizing zone of a flame, there would remain a thick thread of zirconium oxid. v

The other alloys behave quite similarly.

- It will be understood, of course, that other platinum metals as, for instance, ruthenium, iridium or rhodium may be united to these alloys. The production of such filaments takes place in a manner entirely analogous to those above described, the finely divided platinum metal being admixed with the paste prior to the making of the preliminary filament, or the osmium of said paste being Patented Se t. 8, 1914.

*ductivity increases rapidly. As soon as the replaced by a very nnely divided alloy of osmium and the other platinum metal or metals which it is desired to add.

Filaments produced in accordance with this invention may be mounted, by fusion, in

the lamp bulbs in the same manner rastos mium filaments or carbon filaments. They may be secured in place by osmium cement in the manner described in my pending ap-.

therewith, r

containing osmium and zirconium alloyed 2. A filament for electric vacuum lamps,

containlng osmium and zlrcomum alloyed therewith, in substantially equal portions.

'Inwitness whereof I hereunto attach my signature, in the presence of two subscribing 20 witnesses.

DR. CARL AUER VON WELSBAGH.

Witnesses ADOLF GALIJA, L; HAIIJNGER. 

